Electronic monitoring and control devices are utilized for purposes such as monitoring of shipment containers and may be utilized for detecting the presence of hazardous content such as radiation and/or explosive devices. Theoretically, interfacing of communication equipment to other electronic monitor equipment outside the shipping container may be done one of two ways: either by utilizing wired interfacing or by wireless interfacing. Due to the immense number of containers to be monitored, however, it is strongly preferable to utilize wireless interfacing. However, wireless interfacing can be problematic due to the use of metal-walled shipping containers such as steel inter-modal containers and aluminum airline freight containers, which reflect electric fields that are typically used in VHF, UHF and MW radio transmissions. Because these containers are closed after loading with freight, attempts to communicate by radio to and from radio equipment located within the container by radio equipment located outside the containers can be difficult. Transmission from equipment inside the container simply reflects from the metal floor, ceiling and walls, never reaching outside the container. Transmission from equipment outside the container reflects from outer metal of the container never reaching to the radio receiver located on equipment inside the container. Accordingly, it would be advantageous to develop methods and apparatus for enabling radio transmission into and out of metal containers.